I didn't receive my second payment.

No one can see your tax return or know what happened.   Assuming you are talking about your 2nd stimulus payment-----did you use the recovery rebate credit on your 2020 tax return to get the 2nd EIP payment?   Was there an amount on line 30 of your 2020 Form 1040?

If so, that was the EIP payment money you said you had NOT yet received.   The IRS cross checks every return with an amount on line 30.   If the IRS thinks they sent you that payment they take it off and reduce your refund because you cannot get it twice.

That credit can also be applied to any debts, child support or back taxes on record with the IRS.   

If the IRS reduced your refund and took away the EIP payment they will send you a letter a few weeks from now to explain why it was taken.

If they took away the credit and you really did not receive the payment then you have to get them to trace it.

If you were issued a payment and have not received it, see How do I request a payment trace to track my first or second Economic Impact Payments?